FIGURE 1.

UL97 phosphorylates Rb on 11 CDK consensus sites during HCMV infection. A, serum-starved HFFs were mock-infected (M) or infected with wild-type (WT) or UL97-null (Δ97) HCMV. At the indicated hour postinfection (hpi), protein lysates were harvested and analyzed by Western blotting with the indicated antibodies. B, Saos-2 cells were transfected with expression plasmids for FLAG-tagged alleles of wild-type Rb or Rb in which CDK consensus phosphorylation residues were replaced with alanines (RbΔCDK) together with either an empty vector (EV) or one expressing HA-tagged WT UL97 or a kinase-deficient (KD) UL97. Lysates harvested 48 h after transfection were separated by conventional (normal) or phosphate affinity (Phos-tag) electrophoresis and analyzed by Western blotting with the indicated antibodies. pS, phosphoserine; pT, phosphothreonine.